1. Field of the Invention
The invention relates o a steering system that includes a rack housing and a drainage device.
2. Discussion of Background
The configuration of a drainage device in US 2012/0152645 A1 will be described with reference to FIG. 5 and FIG. 6. A drainage device 200 includes a drainage case 210, a drainage valve 240, and a seal ring 250. The drainage case 210 has a first drainage case 220 and a second drainage case 230. The drainage case 210 is formed by connecting the first drainage case 220 and the second drainage case 230, which are formed as separate parts, to each other.
The first drainage case 220 has a case inlet port 221. The case inlet port 221 is communicated with a housing space of a rack housing (not shown). The second drainage case 230 has case outlet ports 231. The case outlet ports 231 are communicated with the outside of the rack housing. The drainage valve 240 has a body portion 241 and a flange portion 242. As the flange portion 242 comes into contact with the inner face of the first drainage case 220, the flange portion 242 interrupts communication between the case inlet port 221 and the case outlet ports 231.
In a steering system (not shown) described in US 2012/0152645 A1, water may enter the housing space from the outside of the rack housing. The water that has entered the housing space flows into the first drainage case 220 through the case inlet port 221 of the first drainage case 220. The water in the first drainage case 220 is accumulated on the flange portion 242.
As shown in FIG. 6, when the flange portion 242 is elastically deformed due to the pressure of water, a gap is formed between the inner face of the first drainage case 220 and the flange portion 242. Thus, the water in the drainage case 210 is drained out of the rack housing through the case outlet ports 231.
In the drainage device 200, a restoring force of the flange portion 242 of the drainage valve 240 may be reduced as the flange portion 242 is deformed repeatedly. If the restoring force is significantly reduced, a gap is formed between the flange portion 242 and the inner face of the first drainage case 220 when no water is accumulated on the flange portion 242. Therefore, foreign matter may enter the housing space of the rack housing from the outside of the rack housing through the case outlet ports 231.